"Cold spot" on my heated bed?

[old man emu]

You raise some good points, Printbus. I've put aluminium cooking foil between my heat bad and glass, and cork sheeting underneath the heated pad. This was in response to thoughts in a thread. I think that the aluminium foil would distribute the heat across the glass.

If I remember correctly, my heater pad was bowed in the middle a little. I did try to take the bow out by putting some 1/4 x 1/4 stick under the centre of the bed, but then I took it away because I figured that the glass was flat. I don't think the stick helped much.

The more I think about it, the more I approach the conclusion that the best way to stop this lifting problem is to:
1. Give the heated bed some time to stabilise its temperature. Perhaps it would be wise to let it heat for about 10 minutes before starting a print.
2. Lay down at least 2 layers at 0.2mm at a speed of about 30mm/second
3. Put a raft under the print, and a skirt around it.

OME

[Roxy]

4. Print big parts in PLA.

Incidently... When you get your Auto_Bed_Leveling going... And we add the enhanced G29 code to produce the Topographical map of your bed... You are going to be amazed at how not flat your glass is. There will be parts of your bed that you avoid on certain types of prints.